US Air Force's X37B 'Secret Space Plane' Marks Two Mysterious Months In Orbit (PICTURES)

22/02/2013 08:22 | Updated 23 April 2013

The US military has had a robotic space plane in orbit around Earth since December - and no one knows what it's doing.

The US Air Force's X-37B space craft is a reusable, currently unmanned vehicle similar - though smaller - than the retired Space Shuttle.

The Boeing-built X-37B is about 30 feet long, 15 feet wide, weighs 11,000 pounds and can carry about the same load as a delivery van.

It took off from Cape Canaveral on 11 December, carried by an Atlas V rocket.

It is the same vehicle which spent 225 mysterious days in space in 2010 before landing automatically in California - and as such marks the first time the US Navy has successfully reused space hardware.

X37B

Officially named USA-240, the current mission is also known as Orbital Test Vehicle-3 since it is the third time the craft has flown.

A report by Space.com did not turn up details about what the space plane is doing - but still makes for fascinating reading.

Among the choice quotes is this by Air Force Maj. Eric Badget, who says simply: "The mission is ongoing".

Enlightening.

In a fact sheet, the Air Force says simple that the X-37B is developed "to demonstrate a reliable, reusable, unmanned space test platform for the United States Air Force".

It is commanded by the 3rd Space Experimentation Squadron, 21st Space Wing, of the Air Force Space Command in Colorado.